Technical Field
The present disclosure relates to organic electroluminescence displays.
Description of Related Art
An electroluminescence display is a kind of flat panel displays. The electroluminescence display includes an electroluminescence layer between two conductive layers. When an electric current flows through electroluminescence layer, the electroluminescence layer emits visible light. An organic electroluminescence display is an electroluminescence display of which the electroluminescence layer is made of one or more organic materials. More specifically, the organic electroluminescence display employs organic light-emitting diodes as its display elements.
Generally speaking, pixel circuits of the organic electroluminescence display control the electric currents flowing through the organic light-emitting diodes by driving transistors. The channels of the driving transistors can be formed by excimer laser annealing (ELA). However, the channels of the driving transistors formed by ELA may have non-uniform crystallization. The non-uniform crystallization leads to variations of the electric currents flowing through the channels of the driving transistors. That is, different electric currents may flow through the channels of the driving transistors in response to the same signals. The variations of the electric currents result in non-uniform luminance. The luminance deviations occurring in groups or periodically lead to mura defects, which are unfavorable features for an observer.
Some manufacturers tried to design pixel circuits to eliminate mura defects. The followings are some architectures for pixel circuits, such as: the 4T1C (4 transistors and 1 capacitor) architecture, the 4T2C (4 transistors and 2 capacitors) architecture, the 5T1C (5 transistors and 1 capacitor) architecture, the 6T1C (6 transistors and 1 capacitor) architecture, and the 6T2C (6 transistors and 2 capacitors) architecture etc. However, the pixel size is getting smaller with the increasing display resolution. Therefore, it becomes more and more difficult to form a complex pixel circuit in a small pixel.